Device for lifting railway tracks



Aug- 11, 1964 E. ovlLLE I 3,143,974

DEVICE FOR LIFTING RAILWAY TRACKS Filed May 20, 1959` 5 Sheets-Sheet 1Aug. 11, 1964 .Filed May 2o'I 1959 E. OvlLLE DEVICE FOR VLIFTING RAILWAYTRACKS 3 Sheets-Sheet 2 E. ovlLLE 3,143,974 DEVICE RoR LIFTING RAILWAYTRACKS Aug. 1'1, 1964 Filed MayZO, 1959 3 Sheets-Sheet 5 United StatesPatent ice 3,l43,974 Patented Aug. 1l, 1964 3,143,974 DEVICE EUR LIFIINGRAILWAY TRAC Eugne ville, Lausanne, Switzerland, assigner to MatrielIndustriel SA., Lausanne, and Constructions Mcaniques SA. Renens,Renens, Switzerland Filed May 20, 1959, Ser. No. 814,615 Claimspriority, application Switzerland May 23, 1958 5 Claims. (Cl. Ilm-12) Inthe course of installation or maintenancework on railway lines, it isoften required to place and to maintain temporarily in an exact positionin a plane which is transversal to the line, one or the other, or boththe heads of the rails, and this at one or at several points of the lineaccording to requirements.

In particular, a precise positioning in height is required for thelevelling operations and transversally to the line for thealigning'operations. It is clear that the problem is similar for anydirection in the transversal plane and .the case of the levelling of theline will be examined more particularly.

The correct positioning in height here olfers particular difficultiesowing to the precision required either in respect of the transversalinclination of the rolling plane (or warp), or in respect of thelongitudinal profile of the line of rails.

Often, however, one has had to be satisfied with simple lifting andwedging devices, such as wedges, extensible wedges, mechanical,hydraulic or electric jacks, often combined with rail clamps, which inturn were sometimes suspended from frames, portals, ete-movable alongthe line or not or again from maintenance machines such as tampingmachines, wedging machines, etc.

In order to obtain greater precision, improved systems have also beenproposed which comprise at least one jack operating as a servo-motorconstantly tending to increase in length and consequently to lift thetrack, until a contact comes to rest against a fixed stop, thus stoppingthe lifting motion. If for instance the point supporting the servo-motorsubsides, the latter automatically increases its length, untilcompensation is achieved.

All these known systems, the operation of which is in effect the same asthat of an extensible wedge, either automatic or otherwise, have acommon defect which resides in the fact that the thickness of the wedgecan only be reduced by manual adjustment, which is left to the operatorsjudgment. The result is that the prescribed level for the rolling planealso depends, on the one hand on the iixity of the supporting point, andon the other on the rigidity of the wedge itself, and eventually, onthat of the support or supports between the rail and the point ofsupport.

Multiple disadvantages, which are very troublesome in practice, resultfrom this, owing to the numerous causes which can modify, either in onesense or the other, in a permanent or transient but always uncertainmanner, either the level of the point of support or the height betweenthe rail and the point of support.

i It will be sufcient to mention the placing of a second jack (owing tothe rigidity of the rail, for instance), the vibration tamping which isusually effected under the sleeper to increase the firmness of thewedged point (and which generally tends to lift the track), theapplication of a variable load over the point of support (for instancethe passage of a loaded axle), the irregular and uncertain elasticityand plasticity of the bed of ballast and of the subgrade, the accidentaldisplacement of a rail clamp in relation to the rail, the springsuspension of the vehicle supporting the clamps, the momentary defectiveadjustment of the reference stop of a servomotor (for instance liftingand lowering following vibrations), etc.

It is thus necessary to touch up the initial bedding, and the touchingup operations must in addition be preceded and followed by relativelyprotracted and'delicate measuring and checking operations, which are allthe more numerous as one is never sure at any given moment of the exactlevel of each of the adjusted points. These disadvantages are the causeof others, the most serious of which are the necessity of employingsupplementary labor, a lengthier period during which the line is out ofservice, higher costs, etc.

It may be mentioned here that similar dilliculties and disadvantages areencountered when the line is being aligned.

The present invention aims at eliminating these disadvantages by meansof a device operating as a servomotor (reversible) which isautomatically controlled in both directions in function of theprescribed position in the transversal plane, for one at least of theheads of the rails.

The object of the present invention is a device for lifting railwaytracks, characterized in that it comprises at least one servo-motorwhich can be controlled in both directions, to place and maintain atleast one line of rails in a predetermined position in a plane which istransversal to the track and in relation to a lxed point, and meanscontrolling this servo-motor, in the abovernentioned two directions, infunction of the position of the rail in relation to the said fixedpoint, so as to 'ensure that this position this maintained.

The accompanying drawings illustrate in a schematic manner and by way ofa non-limiting example, an embodiment ofthe device according to theinvention, in the case of the levelling of the track.

FIGURE l is a schematic side view of this embodiment, showing a partialcross-section along 1--1 in FIG- URE 2. Y

FIGURE 2 is a simplified frontal view of the servomotor itself, along2-2 in FIGURE 1.

FIGURE 3 is a hydraulic scheme showing the essential elements of thecontrol.

FIGURE 4 refers to one of the elements of the scheme shown in FIGURE 3.

FIGURE 5 shows a variant of the same element. FIGURE 6 concerns avariant.

' On the left may be seen a lirst vehicle, or measuring vehicle, thefour anged wheels 4 of which carry a chassis 5 on which are fixed thegeneral supply motor-pump 6 and an oil tank in which the control membersare lodged. Two lingers, only one 8 of which is shown, emerge from thistank plumb over each line of rails and in a plane x situated at equaldistances from the front and rear wheels 4 of the car, whilst a singlestart-stop push-button 9 is provided.

'Ihe lifting device itself is harnessed tothis measuring vehicle and isarranged symmetrically in relation to the Two hydraulic jacks in FIGURE1 to the extremities of a transversal beamseen in cross-section-made upof two profiles of U- shaped cross-section 12 and 13, between which arearticulated in 14 and 14a, two levers 15 and 15a provided with hooks 16and 16a and connected to the articulations 17 and 18 of a hydraulic jack19 called the clamping jack. The two wheels 20 of this lifting vehicleare mounted on two levers 21 pivoted in 22 to the base f theabovernentioned prole 13 and against the upper part of which they abutby means of their respective adjusting screws 23. In a similar manner,the central drawbar 24, which is articulated at both extremities 25 and26, abuts against the other profile 12 mentioned above, by means of itsadjusting screw 27.

In order that the drawing may be clearer, the ducts and auxiliarymembers have not been shown.

Two adjusting stops, one of which only 28 is visible in the drawing, arearranged in the measuring plane x above each of the lingers 8 mentionedabove and are secured to an auxiliary device of any suitablekindpartially shown by dotted lines-which rests on the ground, theballast or the rails at a suiciently great distance from the describeddevice to remain uninlluenced by it.

FIGURE 2 illustrates with the same references, a part of the componentsof the lifting apparatus.

The operation is then as follows:

In the position shown, the lifting apparatus is suspended from threepoints, i.e., 25 and the two wheels 20, by the action of the drawbar andof the two levers 21 abutting against the profiles. In reality the bases11 and the hooks 16 have sufficient clearance in height to avoid anyobstacle on the track and to allow the free motion of the device.

When the later has been immobilized at the desired point, thepush-button 9 is actuated thus starting off the operation of the liftingcontrol. Owing to the action of the clamping jack, the hooks 16 engagethe underside of the heads of the rails, whilst the vertical jacks causethe bases 11 to be pushed down against the ballast. As the pressure inthese jacks increases, the transversal beam 12-13 is lifted and draws upthe clamping levers 15 with it, and thus lifts the two rails and theirsleepers.

This lifting motion of the track continues until each of the railshaving reached its prescribed level, the corresponding finger 8 comeslightly in contact with its stop 28 which is adjusted in consequence.

If for any reason, for instance if the points of support 11, 11a arelowered because the ballast subsides, or if the clamp slips slightly onthe rails, or the level of one of the rails subsides, Athe correspondingfinger 8 is released and causes the lifting motion to be renewed. If, onthe contrary, the point of support 11 or 11a is raised, or if the levelof the rail exceeds the required height, or again if the stop 28 islowered, etc., the finger 8- is pushed in and causes the requiredlowering of the rail, as will be seen further on. It is easy to see thatthe level of each of the rails can thus be maintained exactly at theprescribed value.

When the stop push-button is released, the three jacks bring thecomponents back to their initial positions.

The screws 23 and 27 allow the adjustment, according to the wear of therail, for instance of the height between the hooks and the heads of therails, so as to limit at will the lost lifting motion of the transversalbeam.

It may be noted that when the latter is lifted, the screws 23 and 27leave their rests against the U-shaped profile irons so that the beamhas a certain angular freedom which avoids the loading of the measuringcar at 25. On the other hand, the flanged wheels 20 continue to guidethis beam transversally to the track. v

Finally, it may be remarked that a certain difference in the level ofthe rail may occur between the measuring plane x and the lifting planey, a difference which de- '4 pends on the undulation which is thuscreated along the line of rails owing to the effect of the liftingmotion.

It is clear that the distance between x and y can be adapted accordingto the requirements. In particular, it is possible to annul it withoutany difficulty, by cornbining in a single four-wheeled truck the twoparts, measuring and lifting, of the described device.

In the hydraulic scheme of FIGURE 3, part of the components which havealready been described have been shown again-with the same references-inparticular the transversal beam 12-13 with its two servo-motors 10 and10a and the clamping jack 19 on the one hand, and on the other-mountedon the tank 7-the start-stop pushbutton 9, and the two lingers 8 and 8asurmounted by the corresponding exterior stops 28 and 28a.

Pistons 29, respectively 29a and 30 can slide in the jacks 10, 10a and19 forming the chambers 31 and 32 for the first, 31a and 32a for thesecond and 33, 34 for the last. The three chambers 32, 32a and 34 aredirectly connected together by the conduit 35 which on the other handleads to the start-stop distributor 36, which in its turn is fed on theone hand-through the conduit 37, the check valve 38 and the conduit39-by a large delivery pump 4tlcalled the rapid advance and withdrawapump-and on the other hand by a high-pressure pump 41-the regulatingpump-through a conduit 41 which opens into the chamber 33 mentionedabove. This conduit also leads to two distributing relays 43 and 43a towhich the chambers 31, respectively 31a of the vertical servo-motorsmentioned above are connected by the conduits 44, respectively 44a.

The chambers 45 and 45a of these relays 43, respectively 43a,communicate, on the one hand with 39 by means of the two conduits 46,respectively 46a, each of which passes through a diaphragm 47,respectively 47a, and on the other hand with two distributors 48,respectively 48a-called regulating distributorsby means of two conduits49, respectively 49a.

The ve distributors 36, 43, 43a, 48 and 48a mentioned above have theirslide-valves 50, respectively 51, 51a, 52 and 52a, constantly biased bysprings 53, respectively 54, 54a, 55 and 55a, tending to return them inthe upward direction or towards the centre of the ligure. The bodies ofthese distributors are iixed inside the tank into which they can thusallow their oil to escape through the respective openings 56 and 57, 58and 58a, 59 and 59a.

Two levers 60 and 60th-shown in dots and dashesare articulated in 61,respectively 61a, on the tank and are engaged by one of theirextremities in a groove 62 provided on 9, and can rest by the other onthe collar 63, respectively 63a provided on each finger S and Samentioned above.

The conduit 42 of the regulating pump is connected in addition to adischarge valve 64 the regulating spring 65 of which isactuated-betweencertain limits determined by the adjustable stops 66 and 67-by thepiston 68 of the cylinder 69 which is provided with a chamber 7@ havinga calibrated outlet opening 71 (diaphragmed) and is connected by theconduit 72, diaphragmed in 73, to two check valves 74 and 74a fedthrough two conduits 75, respectively 75a, which in turn lead to theconduits 44, respectively 44a already mentioned.

The sectionsshown by dottedv lines*of the conduits 35, 42, 44 and 44a,are flexible, articulated or sliding tubes to allow relative motionbetween the components that they connect together.

' The operation is then as follows:

In the position shown, the push-button 9 is in its upper position, orstop position, so that the slide-valve 50 connects 42 with the dischargethrough 56, which releases the pressure in the pump 41 and the chamber33. On the other hand, 34, 32 and 32a are subjected to the pressure ofthe pump 40 through 39, 37 and 35, since the check valve 38, ofwell-known design, only opposes a negligible resistance in thisdirection. A certain amount of fluid flowsat a very low rate because of47, respectively 47a-through 46, respectively 46a, to the chamber 45,respectively 45a, connected to discharge through 49 and 59, respectively49a'and 59a, so that the slide-valves 51 and 51a, respectively biassedby 54, respectively 54a, connect 44, respectively 44a, with thedischarge 58, respectively 58a, and thus annul all pressure in 31 and31a, as well as in 75 and 75a. The pressure in 72 and 70 is alsozero-because of 71-and 6s compresses 65 to a minimum determined by theadjustment of 67.

The three jacks are thus maintained in the withdrawn position by 40,whilst 41 delivers at no appreciable pressure, and therefore with agreatly reduced power consumption.

When the push-button 9 is pressed down to the start position, theslide-valve 50 connects 35 to 57 so that the pressure drops in 32, 32aand 34, whilst 37 communicates with 42 cut oic from 56. The pressure dueto 40 and 41 rises progressively in 42, and therefore in 33, so that theclamping jack 19 is immediately actuated.

Simultaneously, 62 causes 60 and 60a to swing so that they move awayfrom 63, respectively 63a, thus releasing the slide-valves 52 and 52a,which rise under the action of their spring 55, respectively 55a, andclose 49 and 49a, which causes the pressure to increase in the chambers45, respectively 45a, which continue to be fed through 46, respectively46a, and 39, 40. The slidevalves 51 and 51a compress their respectivespring 54 and 54a, and connect 42 and 44, respectively 44a-which are cutoff from 58, respectively SSa-so that 31 and 31a are subjected to theincreasing pressure due to 40 and 41, which causes 29 and 29a .to movein the downward direction.

Thus the two pumps 40 and 41 simultaneously feed the three jacks 19, 10and 10a, the motion of which is therefore very rapid during this periodof approach-owing to the fact that there are only small opposingresistanceswhich lasts untilcontact occurs between 16 and 1,respectively 16a and la, 11 and 11a and the ballast 3.

At this moment, the pressure still being on the increase, the beam islifted, pulling the hooks 16 and 16a up with it which engage under theheads 1, respectively 1a, of the rails. This period, which is veryshort, can be considered as forming part of the period of approach.

According to the type of tamping machine used, the track may have atendency to lift by the action of the spades at the end of the tampingoperation. It is then advantageous to provide a device which loads therail, for instance at the point of measurement. A simple solutionconsists in resting a heavy mass on the rail above the sleeper which hasto be tamped, and which will then be lifted by the servo-motor at thesame time as the rail. The mass M can be seen in FIG. 1.

At the same time, the pressure being on the increase in 75 and 75a,fluid flows at a progressively increasing rate through 74 and 74a into70, from where it escapes through 71, the rate remaining however verysmall owing to 73 and 71. The pressure drop across 71 induces a certainpressure in 70, which does not however move 68, retained by the spring65-supposing that the latter is suliiciently compressed in its minimumposition of adjustment, imposed by 67-controlling the discharge valve64, the principle of which is well known and which then prevents anyiluid escaping through it from 42.

When the pressure in 42 becomes equal to the maximum pressure which canbe furnished by the pump 40- Which may be supposed to be, for instance,of the centrifugal type-the check valve 3S closes and the pressure in 42continuesto increase owing to the elect of the high pressure pump 41 andit may be seen that 68 is finally caused to move, thus compressing 65more and more, which keeps 64 in the closed position.

When there is suicient pressure in the circuit 42, the rails and tracksare lifted thus causing the measuring truck to move in the upwarddirection, as previously indicated, and the general movement continuesuntil one of the lingers, for instance 8, comes lightly to rest againstthe exterior point of reference 28, which, to simplify the explanation,is taken to be fixed. The slide-valve 52 is progressively pushed intothe body of its distributor 48, which eventually causes 49 tocommunicate slightly with the discharge 59 which decreases the pressurein 45. The slide-valve 51 tends to cut olf 44 from the feed line 42 toput it practically simultaneously in communication with the discharge 58according to the well-known double edge control method. The liftingmotion of the servomotor 10 is thus arrested, independently of that of10a Which is only arrested at the moment of contact-between 8a and 28a,according to a process similar to the previous one.

It is easy to understand that, Vas has already been said, the exactlevel of each rail, measured in the plane x of FIGURE 1 by the meanposition of the truck on its wheels, can be maintained as long asdesired and independently as long as desired and independently of anymodification other than the adjustment in height of one or of the otherof the reference stops 28 or 28a, which operation only requires a verysmall effort. In short, it may be said that the level of the rails willfaithfully folloWthe level of the fingers 8 and 8a in both directions bythe action of the servo-motors thus controlled, not in effort, but inposition, and in a reversible manner, i.e., in both directions ofadjustment of these servo-motors.

It may also be understood that, if the stop 28 or the rail itself, orboth, are subjected tof vibrations, due for instance to tampingoperations, it is still possible to control with precision the level ofthe track-according to the mean position-extreme or intermediate-of theVibrating elements-by appropriate means, such as means to damp themotion of the slide-valve 51 for instance, which are within the scope ofthe man of the art.

It can be Vseen easily that the three jacks are brought back to theirinitial position by releasing the stop pushbutton 9. Y

Without entering into further detail concerning the operation, it isdeemed suicient to mention that the two check valves 74 and 74a visiblyprevent any mutual inuence between the two individual controls 10 and10a, and at each instant allow the greater of the two pressuresobtainingrin 31 and 31a to be applied to 75, this pressure thendetermining in 42-by a judicious choice of the dimensions of thecomponents of the assembly 64/ 69--a pressure which is constantlyslightly higher. The' power required to drive the pump 41 is thusreduced to a minimum at any instant.

FIGURE 4 reproduces-with the same references-a part of the hydraulicscheme of FIGURE 3 and shows in addition the distributor-relay 43a withits controlling distributor 48a, but with their slide-valves 51a,respectively 52a, in a middle position corresponding to the adjustmentfor Amaintaining a static lifting load. may be seen that the governingedges of the slide-valves and of the bodies are adjacent to one anotherin '76, 77 and 78 so as to create the desired presure in 45a and 44aaccording to a technique Well-known to the man of the art.

It is sucient to underline the fact that in this control. system, adierence in height-measured from the mean position-between theside-valve 52a and the body 48a is transformed into a pressurevariation-measured from the mean maintaining pressure-in the pressurechamber 31a of the servo-motor 10a. It is thus possible to amplify or todemultiply at Will-according to the chosen dimension or to thecomponents-the eifect of the said differences on the control of thedevice, which, for instance enables the precision to be increased, theconditions of stability of operation to be improved, etc.

FIGURE 5 shows a variant of the construction of the control group ofFIGURE 4 which is based on another mode of amplification of thevariations in height mentioned above.

Here the members 43a and 48a are united in a single casing 79. Theslide-valve 80 of the relay is constantly biassed-towards the right inthe ligure-by the pressure-which, to simplify things, is supposedconstantobtaining in 39, 46a, the chamber 81 and the boring 82 drilledin the slide-valve 80. The screw 83 allows the adjustment of thepressure obtaining in the duct 84-in permanent communication with thechamber 85-which bends inside the rectangular head 86 which terminatesthe rod 87 prolonging 80, and ending in an opening 88 over an inclinedplane S9 formed at the bottom of the opening 90 with parallel faces-toguide 86 and 89- formed in the new finger 91 which slides in 79 and isconstantly biassed in the upward direction by the spring 92.

The operation is then as follows:

The slide-valve 80 which for instance has an annular cross-section in 85which is double the annular crosssection in 81, is balanced when thepressure in 85 is half the constant pressure in 81. If the pressure in85 is lower the slide-valve moves-towards the right in the figure-untilthe opening 88 is partially closed by 89. It is obviously to be seenthat the slide-valve 80 is cornpelled to reproduce faithfully-in thehorizontal direction and with a certain ratio of amplification,determined by the inclination 89--the vertical movements of the linger91 in relation to its casing 79. The operation of the distributing relayin the main circuit remains unchanged.

As has been previously indicated, the pressure of the fluid acting in aservo-motor, for instance 31 in FIG- URE 3, can actuate the measuringand control member 68, regulating, through 64, the power absorbed by thepump 41. This pressure-or any magnitude related to the motive uid-canalso influence other devices, for instance entering into a more or lessautomatic system.

It is thus that-as is indicated schematically in FIG- URE 6-the conduit75 (of FIGURE 3) can be permanently connected to the chamber 93 of arelay 94 the piston 9S of which is constantly biased in the downwarddirection (in the figure) by a spring 96 which can be adjusted by ascrew 97. When the pressure reaches the value which has thus beenpredetermined, 95 is lifted and causes-by the action of a distributor98-the closing of the conduit 99 feeding the hydraulic membercontrolling the closing of the spades of the tamping group 189, whichmay be of any usual type.

One may note here the important practical advantage of a servo-motor theposition of which is controlled in both directions and which can thenact as a dynamometer indicating the vertical thrust exercized by theballast on the sleeper which is being tamped, and can thus be used toarrest the closing motion of the spades, etc.- whereas up to now it wasdeemed suicient to act in function of the horizontal thrust to which thespades were subjected in the ballast, which obviously occasioned errorsin the evaluation of the degree of tamping achieved.

According to the type of tamping machine used, the track may have atendency to lift by the action of the spades at the end of the tampingoperation, for instance. It is then advantageous to provide a devicewhich loads the rail, for instance at the point of measurement. It iseasy to imagine the simple solution consisting of a heavy mass restingon the rail above the sleeper which has to be tamped, and which willthen be lifted by the servo-motor at the same time as the rail.

As there are two regulating elements available, position and pressure,it is in addition possible to provide such stabilizing loads, which maybe constant or variable, permanent or temporary, and influenced by oneat least of these elements.

Many constructional variants can be imagined within the scope of theinvention. It may be sufficient to mention the application of the newsystem to any given direction of the transversal plane of the track, inparticular in the case of the aligning operations already mentioned, theuse of a single servo-motor or on the contrary of more than one twinservo-motor, the combination for the simultaneous levelling and aligningoperations, the systems controlled by periodic impulses, the devicesactuated or controlled mechanically, by a pressure fluid (oil, air,etc.), electrically or by magnetic means, etc., etc. The examples givenare therefore in no sense limitative.

It may be seen that the described device is distinguished in that itcomprises at least one servo-motor automatically controlled in functionof the position prescribed for at least one of the rail heads and in aplane transversal to the track (servo-motor influenced by the positionof the rail). It may be:

Adapted for levelling operations;

Adapted for aligning operations;

Combined for levelling and aligning operations;

Controlled by periodic impulses;

Controlled in a continuous fashion;

Operated at more than one speed, operated at variable speeds (rapidapproach and withdrawal, slow adjustment);

Actuated or controlled: mechanically, by pressure fluid,

electrically, by mixed means;

With the position of the measuring point distinct from that of thelifting point (along the track);

With a difference in position which is amplified or demultiplied (atwill, automatically);

With a difference in position transformed into another physicalmagnitude (for instance pressure, stress, flow).

According to a further embodiment of the invention, the device forlifting can be secured to the support chassis of a tamping machineinstead of having the ballast as a fulcrum.

What I claim is:

l. A device for the automatic shifting of a railway track to apredetermined position and for maintaining the track in said position,said device comprising: hydrauically actuated shifting means forshifting the track, means supporting said shifting means and in turnsupported on said track and movable with said track as the latter isshifted, means for establishing the position to which said track is tobe shifted, control means for said shifting means, said control meanscomprising a casing supported in fixed relation on said means supportedon said track, sensing finger means supported on the latter means forsensing the position of the means which establishes the position towhich the track is to be shifted, and pressure fluid distribution meanswithin said casing and controlled by said sensing finger means for inturn controlling fluid distribution to said shifting means to stop theflow of pressure fluid to and from said shifting means to cause shiftingof the track in opposite directions in response to the respectivedirection of actual deviation of the track with respect to saidpredetermined position.

2. A device for the automatic lifting of a railway track to apredetermined level and for maintaining the track at said level, saiddevice comprising: hydraulically actuated jacks adapted for a raisingand lowering function, means operatively associated with the jacks forengaging the track to raise and lower the same in accordance withraising and lowering of the jacks, means supported on said track forbeing moved therewith as the track is raised and lowered, stops forestablishing the level to which said track is to be lifted, controlmeans for said jacks, said control means comprising a member in fixedrelation with said means supported on said track, sensing nger means forsensing the position of said stops, pressure fluid distribution meanswithin said member and actuated by said sensing finger means forcontrolling the fluid distribution to said jacks, said fluiddistribution means stopping the flow of pressure fluid to and from saidjacks with the track at the predetermined level and permitting pressureuid to pass to and from said jacks for selectively raising and loweringthe track in response to the direction of the actual deviation of thetrack with respect to said predetermined level.

3. A device as claimed in claim 2, comprising a vehicle, a tampingdevice mounted on said vehicle, said tamping device comprising tampingtools and control means for said tools, the latter control means beingoperatively connected to said jacks, the pressure prevailing in saidjacks acting on said control means for said tools.

4. A device according to claim 2 comprising further track loading meanspositioned approximately in line with the finger sensing means.

10 for feeding pressure iluid to said shifting means, one of which pumpsis adapted for supplying large volumes at low pressure and another ofwhich pumps is adapted for supplying small volumes at high pressure, andmeans for preventing the escape of liuid under high pressure through thepump which feeds at low pressure.

References Cited in the le of this patent UNITED STATES PATENTS KershawMar. 1, 1960 Keller Aug. 15, 1961 5. A device according to claim 4,comprising pumps 15 10 and l1). Pub. by Norberg Mfg. Co.

1. A DEVICE FOR THE AUTOMATIC SHIFTING OF A RAILWAY TRACK TO APREDETERMINED POSITION AND FOR MAINTAINING THE TRACK IN SAID POSITION,SAID DEVICE COMPRISING: HYDRAULICALLY ACTUATED SHIFTING MEANS FORSHIFTING THE TRACK, MEANS SUPPORTING SAID SHIFTING MEANS AND IN TURNSUPPORTED ON SAID TRACK AND MOVABLE WITH SAID TRACK AS THE LATTER ISSHIFTED, MEANS FOR ESTABLISHING THE POSITION TO WHICH SAID TRACK IS TOBE SHIFTED, CONTROL MEANS FOR SAID SHIFTING MEANS, SAID CONTROL MEANSCOMPRISING A CASING SUPPORTED IN FIXED RELATION ON SAID MEANS SUPPORTEDON SAID TRACK, SENSING FINGER MEANS SUPPORTED ON THE LATTER MEANS FORSENSING THE POSITION OF THE MEANS WHICH ESTABLISHES THE POSITION TOWHICH THE TRACK IS TO BE SHIFTED, AND PRESSURE FLUID DISTRIBUTION MEANSWITHIN SAID CASING AND CONTROLLED BY SAID SENSING FINGER MEANS FOR INTURN CONTROLLING FLUID DISTRIBUTION TO SAID SHIFTING MEANS TO STOP THEFLOW OF PRESSURE FLUID TO AND FROM SAID SHIFTING MEANS TO CAUSE SHIFTINGOF THE TRACK IN OPPOSITE DIRECTIONS IN RESPONSE TO THE RESPECTIVEDIRECTION OF ACTUAL DEVIATION OF THE TRACK WITH RESPECT TO SAIDPREDETERMINED POSITION.